绿色食品产地土壤重金属空间分布与污染评价

Distribution and Evaluation of Soil Heavy Metal in Green Food Producing Area

为研究绿色无公害食品产地土壤重金属的含量与分布状况,以慈溪市周巷镇为研究区,利用综合指数法对土壤中重金属的含量进行评价,应用地统计学的方法分析土壤重金属含量的空间变化,并绘制土壤重金属的空间分布图。结果表明:以当地土壤重金属的自然背景为评价标准,所研究的8种重金属单项污染指数均大于1,说明8种重金属在该区均产生污染。以内梅罗指数法计算的土壤重金属综合污染指数为1.54,处于轻微污染的级别。研究区由北向南随地理位置和土地利用方式的不同,土壤中重金属含量有逐渐增高的趋势。不同剖面土壤重金属含量的研究表明,土壤中重金属有表聚和亚表聚的特征,随取样层次的加深,土壤中的重金属含量逐渐减少,说明土壤中的重金属含量受到人类活动的强烈影响。

To research the content and concentration of heavy metals in soil of green food producing areas, the study was performed in a town named Zhouxiang in Cixi city. The study evaluated the heavy metal contents in soil using the integrative index approach, and based on the ge＇o-statistical method, analysing the distribution of heavy metal in soil and drawing the distribution figures. The results showed that all the single polluted index of eight heavy metals was exceed 1, this suggests that all the heavy metal elements bring the pollution to soil in this area. The integrative index calculated by Nemerow method is 1.54, suggests that the soil is belongs to the slight pollution level. With the change of location and land use type, heavy metal contents in soil increase from north to south. The research of heavy metal in different soil profiles showed that heavy metal assembles in top soil or sub- soil, the contents of heavy metal in soil decreasing with the sample layer deep added, these suggests that heavy metal in soil of this area is strongly affected by human being.